Dell Optiplex 740 - Fan at FULL SPEED - General Hardware - Desktop - Dell Community

Dell Optiplex 740 - Fan at FULL SPEED


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Dell Optiplex 740 - Fan at FULL SPEED

  • Hello, i have a Dell Optiplex 740 AMD-ATHLON 64bit 2.4GHZ core 2 Duo 5000+

    Recenlty purchased i am having a serious problem, bought it off at a seconf hand shop for cheap and i've installed Vista Ultimate 64x on it, i was told the fan was loud but when turning it on the fan runs at FULL SPEED and doesnt slow down even when the PC is not running any serious applciations!

    I've tried looking every where to see if there's a fix for it, i recently updated the BIOS hoping to resolve it but no Joy....

    I even pressed F2 at start up to see if i can control the fan speed there but dells dont seem to support that feature.

    I'm really stuck for things to look for, maybe the heatsink is not seated correctly or the fan's bearings have worn so it cant slow down, who knows....

    it runs so fast it makes my hoover look bad and it completely freezes my small room and its basically unbare-able

    Please can anyone help, is there a program i can install that can give me a temporay fix or solution? any suggestions a knowledgable advice will be appreciated.
  • My dept @work has old GX270s (can't complain, 2 yesrs ago, my dept was still using Compaq P166s w/32MB - we seem to get the leftovers from other depts:(

    Anyway, every once in awhile, one of the machines (have 3), the fan goes full tilt (it's got a squirrel fan). They seem to have 2 or full throttle.

    Hit ctrl-alt-del to get to the Task Manager

    There may be one or more programs/processes stuck, pegging the CPU @100%...

    I would try to figure out the culprit, unless you do a frsh install of the OS (if you haven't already.

    BTW, the ones we have are SFF.
    Message Edited by DeathRider on 04-13-2008 09:14 AM

    XPS M1530 (BIOS A11): Vista Home Premium SP1
    T9300/LG 1680x1050/256MB 8600GT/3GB/200GB FFS/DVDRW

  • Hi Deathrider, thanks fro the information i tried looking in task manager and the CPU is only a 3% and i've just done a fresh install of WIN Vista Ultimate 64bit :(


    I thought it mght be the fans wires where connected directly to the PSU as a result making the fan run at a constant full speed but it doesnt seem that way as on the motherboard teh fans wires are plugged into the small socket labelled CPU FAN, looks like im going to do some more research and find out more!

    Thanks any more help would be apprciated


  • I know this question is REALLY OLD but I was wondering if anyone had found a solution to this?

  • The problem is likely a malfunctioning temp sensor or bios flash memory problem but the OP was lucky in that his system at least booted into the os.

    In my case the bios post seemed to hang and the fan would go full speed while boot would not progress. This occurred on two of my dell machines a couple of years ago but as i was planning to replace them i didn't worry to much.

  • Yes but I sleep in the same room as this computer and need to keep it on all night and the fan is extremely loud and won't stop

  • Bad Capacitors or improperly mounted heatsink can cause the fan to go into airplane mode.

    Keep in mind however that the cooling system in dell's is passive.   There are no refrigeration units.

    If the room is 72 -80 degrees or warmer the fan is not going to cool the machine much.


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